This invention relates to laser sources and amplifiers that produce coherent radiation that has a shorter wavelength than the wavelength of the pumping radiation through an upconversion process, and more particularly to methods and apparatus for such upconverting laser sources and amplifiers that operate with a rare earth doped solid state lasing medium that may be pumped with infrared radiation under ordinary ambient temperature conditions to provide upconverted laser radiation in the blue portions of the optical spectrum.
Laser systems that produce wavelengths in the shorter wavelengths of the portion of the optical spectrum are highly desirable for a variety of applications. These applications include laser based video display systems and optical systems wherein the higher resolutions afforded by short optical wavelengths are important, such as optical storage systems.
Although laser systems have been developed that produce outputs in the shorter wavelengths of the optical spectrum, the value of such systems have been diminished by one or more factors that include high cost, critical alignment and high maintenance. For instance, rare fas ion lasers have both a high purchase price and a high degree of maintenance. Frequency doubling or summing lasers that employ a nonlinear element require critical alignment and high maintenance.
A laser source or amplifier that uses solid state components throughout is a desirable configuration for a low cost, low maintenance system, but such lasers have never been able to achieve operation in the shorter wavelengths of the optical spectrum under normal ambient temperature operating conditions. Furthermore, the prior art has not been able to achieve such operation with a continuous or quasi-continuous pumping source.